Sure, the only touchier issue is the Hand may need to be trimmed for length. I've not run into it, but the info came with a Powers Kit.
Try Brownells or Numrich Arms.
I'd definitely do that before changing the window. And if you do decide to widen the window, Brownells sells a file specifically for that.
I've tried Brownells, no luck there, they do have the new style. I have a window file I just don't want to use it. The only time I've ever used it was replacing a cylinder stop.
I'll try Numrich.